(1) Field of the Invention
The invention relates to a boring device and a boring method for producing a bore and having a support pipe, which is introduced into the soil.
(2) Description of Related Art
A relevant prior art is known from document DE-C-27 34 185. An internal boring device is inserted by a crane into a casing tube arranged in the ground. This known boring device has a cylindrical casing in which the motor for the rotary motion is placed. The boring device is connected to the inner surface of the casing tube by means of clamping device nearby the bottom of the bore hole.
Another method for making a bore hole with a casing tube is known from the document FR-A-15 09 586. A boring auger together with a cylindrical receiving container for receiving the borings are arranged on a linkage. During the boring the borings are conveyed into the receiving container. If it is completely filled, the receiving container and the boring auger are retracted. The receiving container can be released and axially moved away from the boring auger. The drive for the boring auger is arranged on a carriage being movably mounted on a mast.
In the document xe2x80x9cHandbuch des Brunnenbausxe2x80x9d, vol. 1, pages 88 and 89, of Bieske, Berlin 1956, a boring method without using any casing tube is described. For removing the borings from the bore hole flushing lines are used.
When producing foundation piles for building foundations, it is known to initially introduce into the soil a support pipe, e.g. using rams or a vibrating pile hammer. The soil within the support pipe can then be removed by means of a boring device. This is particularly appropriate with relatively loose soil, because the support pipe prevents the giving way of the bore walls.
For removing the soil within a support pipe use is normally made of a soil auger, whose external diameter is matched to the internal diameter of the support pipe. When using a soil auger it is necessary to use a special boring device with a vertical mast, on which the soil auger is vertically displaceable guided and simultaneously retained so as to be rotatable. As the vertical mast, which is normally fitted to a movable mount, can only be tilted by a few degrees, the use of a soil auger in uneven ground or terrain with considerable level differences is problematical. It may be necessary in such a case to initially create a horizontal platform on the support pipe for the boring device with the soil auger.
Moreover, the boring device with a soil auger cannot be used or at best can only be used after protracted equipment modifications for the preceding introduction of the support pipe into the ground.
Therefore the object of the invention is to provide a boring device and a boring method, which permit an efficient production of a bore with a casing tube.
This object is achieved by a boring device and a boring method in accordance with the invention.
The boring device according to the invention is provided with
a linkage with a crane attachment at its upper end,
a boring tool, which can be fixed to the lower end of the linkage,
a mounting frame in which the linkage is held in rotary and axially displaceable manner and which is constructed for mounting on the casing tube,
a drive, which is located on the mounting frame and constructed for the rotary driving of the linkage and
a connecting device for producing a firm connection between the casing tube and the mounting frame, in which
the linkage is hollow and has a first flushing line and a second flushing line and
in the vicinity of the upper end of the linkage are provided a first connection for the supply of a fluid to the first flushing line and also a second connection, which is constructed for removing the borings by means of the second flushing line.
The boring device according to the invention can be used hung on a crane, so that considerable terrain unevennesses or greater level differences between the casing tube and the boring device have no influence on the performance of the boring method. In particular, the boring device hung on a crane cable is vertically oriented in automatic manner, so that there is no need for complicated adjustments for vertical boring purposes.
For effective boring the boring device linkage is constructed in hollow manner and provided with at least two fluid lines. The first fluid line can be used for transporting the borings or mud from the boring tool. The other line is used for supplying a fluid. The fluid can be water or air in order to assist the transporting away of the borings. However, the flushing line can also be used for the supply of a suspension which will harden, so that on extracting the boring device from the bore, the latter can be filled with hardenable suspension, particularly concrete. In order to ensure a reliable torque transmission to the boring tool despite the crane suspension, the boring device according to the invention is mounted with a mounting frame on the upper edge of the casing tube and detachably fixed thereto by means of a connecting device. The connecting device permits a rapid release of the rotary connection, which together with the continuous suspension of the boring device on the crane permits an efficient continuous production of bores.
The connecting device can comprise different positive or non-positive locking devices. According to the invention it is preferable for the connecting device to have hydraulic holding clamps, with which the mounting frame can be clamped to an upper edge of the casing tube. Hydraulically operable clamps permit a rapid clamping and release in the case of high clamping forces.
According to another preferred embodiment of the invention, the first or second connection can have a swivel joint. Thus, the flushing lines rotating with the linkage can be reliably connected to stationary devices, particularly fluid reservoirs located outside the bore. Such a swivel joint generally comprises two rotary flanges rotatable relative to one another and arranged in liquid-tight manner, whereof one is connected to the flushing line and the other to the stationary line.
The most varied devices can be used as boring tools, e.g. a boring bucket. According to the invention it is particularly advantageous for the boring tool to be a full cut boring head and for the boring string to have a hollow construction with two lines, which are connectable with the first flushing line and the second flushing line in the linkage. Such a full cut boring head is particularly suitable for working a hard substrate, e.g. rock. Combined with the removal of the borings by means of the flushing line, it is also possible to make a very deep bore. It is possible to fit to the boring device according to the invention various boring tools, so that for each soil layer to be bored the most suitable boring tool can be used.
According to the invention the boring device is hung by means of a cable on a crane jib and a first hauling cable is fixed to the side facing the jib, whilst extending towards the latter and that on the other side is articulated a second hauling cable, which extends to the upper end of the jib. The boring device hung on a crane jib can consequently be subject to the action of hauling cables and winches from two opposite sides. This makes it possible to prevent any undesired swinging of the boring device and the latter can be easily swung to the side of the crane jib and held in this swung out position. In such a swung out position it is e.g. possible to use the crane by means of a second cable winch for positioning and bringing in the support pipe, without it being necessary to detach the boring device from the crane.
There is at least one flushing line in the hollow linkage. According to the invention the linkage can be constructed as a double-wall linkage, the annular hollow space between an inner core and the outer linkage wall forming the flushing line. The other flushing line can be located on the outside or in a radial internal hollow space of the inner linkage.
The boring method according to the invention is characterized in that use is made of the boring device described hereinbefore and said boring device is hung on a cable of a crane. This makes it possible to efficiently produce a bore with the advantages described hereinbefore.
A preferred embodiment of the method according to the invention comprises producing a first bore within the casing tube, that a boring head with boring string is introduced separately from the boring device into the casing tube and that finally the boring device is firmly connected by means of the linkage to the boring string.
It is possible to make the first bore with a different boring tool, such as a boring bucket or soil auger. The boring tool can be fitted to the boring device according to the invention and used with the latter for making the first bore, e.g. in a looser substrate. Thus, in the support pipe is formed a free space, which can be used for introducing and adjusting a boring head with boring string. This permits using different boring tools to bring about an efficient penetration rate, a full cut boring head with boring string being particularly appropriate for working a hard substrate.
According to the invention, said method is further developed in that the boring head with the boring string is held by means of a holding device in the support pipe in a connection position prior to fixing to the linkage, that following fixing the holding device is released, whilst the boring device continues to be suspended on the cable, and that finally the mounting frame is connected to rotate with the support pipe. This permits a reliable and at the same time rapid connection of the boring string of the boring head to the boring device linkage.
A particularly efficient fixing of the boring string within the support pipe for connection to the linkage is inventively brought about in that the holding device has at least one carriage with a holding fork displaceable radially to the support pipe and in which rests in the holding position a flange of the boring string. In particular, there are two, three or four holding forks uniformly distributed round the circumference of the upper end of the support pipe on a platform. The holding fork width corresponds to the external diameter of the boring string and the larger diameter flange or collar of the boring string rests on the holding fork or forks and consequently in a desired holding position. This permits an easy connection to the boring device linkage outside the support pipe.
In the case of the crane according to the invention, it is advantageously provided that the bore is made with the boring device through the support pipe into an underlying soil layer. It is possible to drive a support pipe into a relatively loose soil. However, if a foundation pile extended beyond the looser soil layer is necessary, initially the looser soil layer within the support pipe can be removed by a first boring tool, e.g. a boring bucket. It is possible to fix and use a second boring tool, particularly a full cut boring head with boring string to the same boring device and it is then possible therewith to remove in an efficient manner a more solid, rocky soil located below the support pipe.
The pressure on the boring tool can be applied by means of a telescopic linkage via corresponding hydraulic pressure cylinders. However, it is particularly effective and energy-saving that during boring the linkage is guided in axially freely displaceable manner in the mounting frame, so that the weight of the linkage presses on the boring tool. The boring string can additionally be provided with loading weights, so that an adequate pressure can be exerted on the boring tool for a speedy penetration rate.
A preferred embodiment of the boring method according to the invention comprises, during boring, flushing air being supplied by means of the first flushing line, whereas via the second flushing line borings can be removed with liquid and flushing or scavenging air. This method permits a particularly efficient transporting away of borings, so that there is a speedy penetration rate.
The invention is described in greater detail hereinafter relative to preferred embodiments and the attached diagrammatic drawings, wherein show: